Just adding these for easy access to anyone who's interested in watching the chemistry between the Main lead's outside the drama. I personally found the 3 lead's chemistry amazing. Even the making videos are fun to watch. Every show they went as a guest to promote was entertaining too.

Behind the scenes:

Script reading(ENG): https://www.youtube.com/watch?v=1MVKQayRTJc

Episodes 1-2(ENG): https://www.youtube.com/watch?v=T8ctfK4jRHg

Episodes 3-4(ENG): https://www.youtube.com/watch?v=6Ay1o0-Ilaw

Episodes 5-6(ENG): https://www.youtube.com/watch?v=t2alLCSKm9I

Episodes 7-8(ENG): https://www.youtube.com/watch?v=y1MrzpnhU7g

Episodes 9-10(ENG): https://www.youtube.com/watch?v=HJGpyVYkzpk

Episodes 11-12(ENG): https://www.youtube.com/watch?v=51VNXaGcLZY

Episodes 13-14: https://www.youtube.com/watch?v=4z2ZiYEN3KQ

Episodes 15-16: Interview: https://www.youtube.com/watch?v=oJ-vkL12JK0

                                     Making: https://www.youtube.com/watch?v=Wu-oQj5VM5c

Drama behind scenes- from Apink YouTube(ENG): https://www.youtube.com/watch?v=9QhDa4RzSG8

Other:

Netflix Q&A(ENG): https://www.youtube.com/watch?v=PnFvWUKMvGI

Commentary by Main cast on Episodes 1-4(ENG): https://www.youtube.com/watch?v=oitB0FNnVIU

Singles Magazine interview(ENG): https://www.youtube.com/watch?v=MjSWFBBfrfU 

Singles Magazine shoot- bts from Apink YouTube(ENG): https://www.youtube.com/watch?v=jCaxiMpAY40

Zzanbro(ENG): https://www.youtube.com/watch?v=iLgW1J4THdQ

Knowing bros(ENG):

https://www.youtube.com/watch?v=jYbmUOWDM5k

https://www.youtube.com/watch?v=iJaiaLIbJkk

https://www.youtube.com/watch?v=bnCjtS17NJE

https://www.youtube.com/watch?v=n2EBiKZrtAU

Dolsing Fourmen(KOR): 

https://www.youtube.com/watch?v=Z3tOJ0IIidY

https://www.youtube.com/watch?v=0AwiAbo6ESc

STAY(OST Part 5) by EUNJI -Making, interview: https://www.youtube.com/watch?v=hwj07Coun9U

Production presentation: https://www.youtube.com/watch?v=yaj3eRKohPM

If you're even more interested, this account on Twitter(still hard for me to call it X) subs most of their content quickly- https://x.com/Tokkidan1

Feel free to comment if you find any other videos.